This invention relates to the field of data networks and, more specifically, to Network Address Translator (NAT) configuration.
The Transport Control Protocol/Internet Protocol (TCP/IP) suite of protocols is used in many of today""s networks. A TCP/IP-based network, such as the Internet, provides a data packet routing system for communication between nodes (e.g., end-user workstations, servers, network devices, etc.) connected to the Internet. In traditional destination address based routing, a source node specifies as a destination Internet protocol (IP) address the IP address of the destination node in an IP datagram. The IP datagram is encapsulated in a physical frame, or packet, and sent to a router attached to the same network as the source node. The router receiving the frame, in turn, parses the IP datagram to determine the destination IP address. The router selects a router enroute to the destination node and again encapsulates the datagram in a physical frame for transmission to the router. This process continues until the IP datagram reaches the network to which the destination node is connected.
Growth of the Internet, as well as private xe2x80x9cintranetsxe2x80x9d, has placed demands not only on bandwidth requirements, but also the Internet routing protocols and the available IP address space. In addition, because of the increased demand for Internet access, the number of available IP addresses is rapidly diminishing and most Internet Service Providers (ISPs) will only allocate one IP address to a single customer. Typically with only one IP address, a user can have only one computer connected to the Internet at one time.
One proposal for overcoming the shortage of IP addresses is set forth in the Informational Request For Comments (RFC) 1631, May, 1994, entitled xe2x80x9cThe IP Network Address Translator (NAT).xe2x80x9d The proposal is based on reusing existing IP addresses by placing NAT software, and NAT tables or databases, at each edge networking devices (i.e., routers or cable modems) between routing domains. The NAT table at each participating router comprises local, reusable IP addresses for use in data packets transmitted within local routing domains, and assigned, globally unique IP addresses for use in data packets transmitted outside local routing domains, that is, over the Internet. There are, though, several limitations associated with upgrading existing edge networking devices to include the NAT feature.
One limitation associated with upgrading an existing edge networking device to include the NAT feature is due to the fact that an existing edge networking device is typically originally configured to have only one MAC address. However, the addition of the NAT feature typically requires an edge networking device to have three MAC addresses; one for the edge networking device, and one each for a DHCP client and a DHCP server associated with the NAT feature upgrade.
Another limitation associated with upgrading an existing edge networking device to include the NAT feature is in the reconfiguration of the edge networking device. The upgrade to include the NAT feature typically requires a user to input configuration parameters, such as MAC addresses or PC hostnames, for proper integration of the new NAT device with the system devices. These parameters may not be known to the user or may be difficult for the user to retrieve.
The invention comprises a method and apparatus (140) for parameter borrowing for network address translator (NAT) configuration.
In one embodiment of the present invention, a method includes receiving, at a first dynamic host configuration protocol (DHCP) device, a DHCP lease request from a client, determining, from the DHCP lease request, first communication parameters of the client, and enabling the determined first communication parameters to be used by a second DHCP device, the determined first communication parameters adapted for use in upstream DHCP lease requests by the second DHCP device.
In another embodiment of the present invention a method includes receiving, at a first dynamic host configuration protocol (DHCP) device, a DHCP lease request from a client, determining, from the DHCP lease request, first communication parameters of the client, enabling the determined first communication parameters to be used by a second DHCP device, the determined first communication parameters adapted for use in upstream DHCP lease requests by the second DHCP device, determining, from a DHCP lease grant sent in response to the upstream DHCP lease request by the second DHCP device, second communications parameters, and enabling the determined second communication parameters to be used by the first DHCP device.
In another embodiment of the present invention, an apparatus includes a first DHCP device, for receiving DHCP lease requests from a client, a second DHCP device, for generating upstream DHCP lease requests, a memory for storing communications parameters and instructions, and a processor. Upon executing the stored instructions, the processor is configured to receive at the first DHCP device a DHCP lease request from a client, to determine, from the DHCP lease request, first communication parameters of the client, and to enable the determined first communication parameters to be used by a second DHCP device, the determined first communication parameters adapted for use in upstream DHCP lease requests by the second DHCP device.